Panel fastener

1. A fastener ( 100 ) for attachment to a panel (P), having an inner skin and an outer skin, via a panel aperture (PA) in the outer skin, comprising:

an insert pillar ( 200 ), a base plate ( 400 ), a spring ( 600 ), and a top insert ( 900 );

the insert pillar ( 200 ) having a pillar proximal end ( 210 ), a pillar distal end ( 220 ), a pillar bore ( 230 ) extending into the insert pillar ( 200 ) from the pillar proximal end ( 210 ) and defining a longitudinal axis of the fastener ( 100 ), and a plurality of pillar lobes ( 270 ) located adjacent the pillar distal end ( 220 );

the base plate ( 400 ) having a base plate proximal end ( 410 ), a base plate distal end ( 420 ), a base plate bore ( 450 ) that extends from the base plate proximal end ( 410 ) to the base plate distal end ( 420 ) and receives at least a portion of the insert pillar ( 200 ), a base plate exterior surface, and a plurality of base plate pillar lobe engagement recesses ( 460 ) that receive at least a portion of the plurality of pillar lobes ( 270 ) and prevent the base plate ( 400 ) and insert pillar ( 200 ) from rotating relative to one another;

the spring ( 600 ) in contact with a portion of the base plate exterior surface and having a spring proximal end ( 610 ), a spring distal end ( 620 ), a spring bore extending into the spring ( 600 ) from the spring distal end ( 620 ) and defining a spring internal surface, and a spring external surface having a plurality of spring slots ( 680 ), extending from the spring proximal end ( 610 ) toward the spring distal end ( 620 ), and a plurality of spring TILP activation features ( 490 ), wherein each spring slot ( 680 ) has a spring slot width ( 682 ), a spring slot length ( 684 ), and a spring slot depth ( 686 );

the top insert ( 900 ) having a top insert proximal end ( 910 ) with a top insert opening providing access to the pillar bore ( 230 ), a top insert distal end ( 920 ), a plurality of top insert latching projections ( 960 ) adjacent the top insert proximal end ( 910 ), a plurality of offset latching projections positioned to cooperate with the plurality of spring TILP activation features ( 690 ), and a top insert interior surface in contact with a portion of the spring ( 600 );

wherein in an uninstalled state the top insert latching projections ( 960 ) are deflectable inward from a first radial position toward the longitudinal axis, through a predetermined TILP displacement, to a second radial position, so that the fastener ( 100 ) passes through the panel aperture (PA) and the top insert latching projections ( 960 ) automatically return to the first position and engage the panel outer skin;

wherein in the uninstalled state the spring ( 600 ) establishes a first stand-off distance between the top insert proximal end ( 910 ) and the base plate distal end ( 420 ), and in an installed state a portion of the spring ( 600 ) is compressed in the direction of the longitudinal axis by application of a longitudinal force against the top insert ( 900 ) with a fastener distal end ( 120 ) restrained by the panel inner skin, thereby reducing the first stand-off distance to a second stand-off distance between the top insert proximal end ( 910 ) and the base plate distal end ( 420 ); and

wherein the longitudinal compression of the spring ( 600 ) produces radial expansion of a portion of the spring ( 600 ) and the spring TILP activation features ( 690 ), causing deflection of at least one of the offset latching projections outward away from the longitudinal axis.

2. The fastener ( 100 ) of claim 1 , wherein each offset latching projection is angularly offset at least 10 degrees from the adjacent top insert latching projections ( 960 ).

3. The fastener ( 100 ) of claim 2 , wherein at least one spring slot ( 680 ) is located between each top insert latching projections ( 960 ) and the nearest offset latching projections.

4. The fastener ( 100 ) of claim 2 , wherein the plurality of top insert latching projections ( 960 ) includes 3-20 top insert latching projections ( 960 ), and the plurality of pillar lobes ( 270 ) includes 3-24 pillar lobes ( 270 ).

5. The fastener ( 100 ) of claim 1 , wherein the spring slot width ( 682 ) is at least 75% of the spring slot depth ( 686 ), and the spring slot length ( 684 ) is greater than the spring slot width ( 682 ) and the spring slot depth ( 686 ).

6. The fastener ( 100 ) of claim 5 , wherein the spring slot length ( 684 ) is no more than 12 times greater than the spring slot width ( 682 ), the spring slot width ( 682 ) is no more than 300% of the spring slot depth ( 686 ), and a spring sidewall thickness is no more than 4 mm.

7. The fastener ( 100 ) of claim 1 , wherein the spring ( 600 ) is formed of an elastomeric material having a spring hardness of 15-45 on a Shore A hardness scale.

8. The fastener ( 100 ) of claim 7 , wherein the spring ( 600 ) creates a friction fit between a portion of the base plate ( 400 ), a portion of the spring ( 600 ), and a portion of the top insert ( 900 ).

9. The fastener ( 100 ) of claim 8 , wherein the spring ( 600 ) is a unitary piece of material that encircles a portion of the base plate ( 400 ).

10. The fastener ( 100 ) of claim 9 , wherein in the uninstalled state the spring ( 600 ) has a spring length measured parallel to the longitudinal axis between the spring proximal end ( 610 ) and the spring distal end ( 620 ), and the spring length is within 40% of a base plate pillar shroud length ( 478 ).

11. The fastener ( 100 ) of claim 10 , wherein the spring length is no more than 12 mm, and the predetermined TILP displacement is 0.25-2.00 mm.

12. The fastener ( 100 ) of claim 7 , wherein the top insert ( 900 ) is formed of nonmetallic material having a density of less than 2 g/cc.

13. The fastener ( 100 ) of claim 12 , wherein the top insert ( 900 ) has a hardness of 100-150 on a Rockwell R scale.

14. The fastener ( 100 ) of claim 12 , wherein the insert pillar ( 200 ) is formed of metallic material having a density of no more than 8 g/cc.

15. The fastener ( 100 ) of claim 7 , wherein a difference between the first stand-off distance and the second stand-off distance is 0.5-5.0 mm when the longitudinal force is 5-50 lbf.

16. The fastener ( 100 ) of claim 15 , wherein in the installed state the spring ( 600 ) biases the top insert ( 900 ) away from the base plate ( 400 ) and produces a biasing pressure on the top insert ( 900 ) of at least 5 psi.

17. The fastener ( 100 ) of claim 15 , wherein a portion of the top insert ( 900 ) engages the spring proximal end ( 610 ) so that the longitudinal compression of the spring ( 600 ) causes the spring proximal end ( 610 ) to deflect inward at least 0.3 mm toward the longitudinal axis and cover a portion of the base plate proximal end ( 410 ), when the longitudinal force is 5-50 lbf.

18. A fastener ( 100 ) for attachment to a panel (P), having an inner skin and an outer skin, via a panel aperture (PA) in the outer skin, comprising:

an insert pillar ( 200 ), a base plate ( 400 ), a spring ( 600 ), and a top insert ( 900 );

the insert pillar ( 200 ) having a pillar proximal end ( 210 ), a pillar distal end ( 220 ), a pillar bore ( 230 ) extending into the insert pillar ( 200 ) from the pillar proximal end ( 210 ) and defining a longitudinal axis of the fastener ( 100 ), and a plurality of pillar lobes ( 270 ) located adjacent the pillar distal end ( 220 );

the base plate ( 400 ) having a base plate proximal end ( 410 ), a base plate distal end ( 420 ), a base plate bore ( 450 ) that extends from the base plate proximal end ( 410 ) to the base plate distal end ( 420 ) and receives at least a portion of the insert pillar ( 200 ), a base plate exterior surface, and a plurality of base plate pillar lobe engagement recesses ( 460 ) that receive at least a portion of the plurality of pillar lobes ( 270 ) and prevent the base plate ( 400 ) and insert pillar ( 200 ) from rotating relative to one another;

the spring ( 600 ) in contact with a portion of the base plate exterior surface and having a spring proximal end ( 610 ), a spring distal end ( 620 ), a spring bore extending into the spring ( 600 ) from the spring distal end ( 620 ) and defining a spring internal surface, and a spring external surface having a plurality of spring slots ( 680 ), extending from the spring proximal end ( 610 ) toward the spring distal end ( 620 ), wherein each spring slot ( 680 ) has a spring slot width ( 682 ), a spring slot length ( 684 ), and a spring slot depth ( 686 ), and wherein the spring ( 600 ) is formed of an elastomeric material having a spring hardness of 15-45 on a Shore A hardness scale;

the top insert ( 900 ) having a top insert proximal end ( 910 ) with a top insert opening providing access to the pillar bore ( 230 ), a top insert distal end ( 920 ), a plurality of top insert latching projections ( 960 ) adjacent the top insert proximal end ( 910 ), and a top insert interior surface in contact with a portion of the spring ( 600 ), wherein the top insert ( 900 ) is formed of nonmetallic material having a density of less than 2 g/cc;

wherein in an uninstalled state the top insert latching projections ( 960 ) are deflectable inward from a first radial position toward the longitudinal axis, through a predetermined TILP displacement, to a second radial position, so that the fastener ( 100 ) passes through the panel aperture (PA) and the top insert latching projections ( 960 ) automatically return to the first position and engage the panel outer skin; and

wherein in the uninstalled state the spring ( 600 ) establishes a first stand-off distance between the top insert proximal end ( 910 ) and the base plate distal end ( 420 ), and in an installed state a portion of the spring ( 600 ) is compressed in the direction of the longitudinal axis by application of a longitudinal force against the top insert ( 900 ) with a fastener distal end ( 120 ) restrained by the panel inner skin, thereby reducing the first stand-off distance to a second stand-off distance between the top insert proximal end ( 910 ) and the base plate distal end ( 420 ), and a difference between the first stand-off distance and the second stand-off distance is 0.5-5.0 mm when the longitudinal force is 5-50 lbf; and wherein at least one spring slot ( 680 ) is located between each top insert latching projections ( 960 ), the plurality of top insert latching projections ( 960 ) includes 3-20 top insert latching projections ( 960 ), the plurality of pillar lobes ( 270 ) includes 3-24 pillar lobes ( 270 ), the spring slot width ( 682 ) is at least 75% of the spring slot depth ( 686 ), and the spring slot length ( 684 ) is greater than the spring slot width ( 682 ) and the spring slot depth ( 686 ).

19. The fastener ( 100 ) of claim 18 , wherein in the installed state the spring ( 600 ) biases the top insert ( 900 ) away from the base plate ( 400 ) and produces a biasing pressure on the top insert ( 900 ) of at least 5 psi.

20. The fastener ( 100 ) of claim 18 , wherein a portion of the top insert ( 900 ) engages the spring proximal end ( 610 ) so that the longitudinal compression of the spring ( 600 ) causes the spring proximal end ( 610 ) to deflect inward at least 0.3 mm toward the longitudinal axis and cover a portion of the base plate proximal end ( 410 ), when the longitudinal force is 5-50 lbf.